Electromedical implants of the aforementioned types are provided in various forms. Such implants usually have a tight housing comprising a power supply and other electronic and electric components to generate stimulation pulses and/or defibrillation shocks, and to deliver them over an elongated electrode line with a longitudinal axis to certain body sites, such as one or more chambers of the heart, a neural pathway, the spinal cord or the brain or to detect and process electronic potentials from these body parts. To this end, such implants are usually connected to electrode lines, which are inserted with a connecting piece on the proximal end of the electrode line into a bushing in a so-called header of the respective implant. The connecting piece and the bushing in the header of the implant have corresponding electrically conducting contacts to establish an electrically conductive connection between the heart stimulator and the electrode line.
In addition to a connecting piece on the proximal end, such electrode lines also comprise a tubular, flexible and bendable electrode body with a longitudinal axis and a distal end which faces the treatment location and at which the electrode poles by which the therapeutic and/or diagnostic signals are received or delivered are located. The electrode poles may assume the form of point electrodes on the distal end or ring electrodes in the vicinity of the distal end or large-area coil segments that serve to deliver shocks.
The electrode body has an electrically insulating outer shell, preferably biocompatible, in which the feeder lines are embedded to protect the feeder lines and insulate them with respect to the body tissue. The material of such a shell may be silicone, for example. In addition, another outer coating may be applied to the insulating outer shell; it may also be biocompatible, have a low coefficient of friction and facilitate the placement of the electrode line. Polyurethane, for example, meets these requirements for the outer coating.
The feeder lines described here serve to transmit measurement signals from the electrode poles to the connecting piece or to transmit stimulation pulses or defibrillation shocks from the connecting piece to the respective electrode poles. One or more of the feeder lines may have a coiled shape which runs within the outer shell. Through this coiled feeder line whose longitudinal axis is situated on the longitudinal axis of the electrode line, the electrode gains elastic properties, which prevent the electrode from breaking or the electric feeder lines from being damaged in the event of a possible mechanical tensile load. In addition, this coiled feeder line forms a lumen from the proximal end to the distal end of the electrode line along which the electrode can be guided on a guide wire or mandrel but through which therapeutic substances such as medicines may also be conveyed.
Furthermore, the electrode line has a kink guard at the transition to the connecting piece, preventing the connecting piece from developing a kink on the one hand while on the other hand serving as strain relief for joined contacts between the electrode feeder line and the connecting piece.